Interposers are utilized for interfacing two electrical components, for example, a semiconductor device and a printed circuit board, or a semiconductor wafer and a probe card for testing of the dies on the wafer. These interposers may comprise silicon or ceramic substrate that include metal-filled vias that extend through the interposer from one side to the opposite side. The metal-filled via provide electrical communication between conductive structures disposed on the opposing surfaces of the interposer, which align with contact pads or other structures of the electrical components to establish electrical connection between the two components.
Continued miniaturization of integrated circuits results in contact vias having increasingly higher aspect ratios (defined as the ratio of height to width of the via).
Conventional methods of filling a through-via using a plasma chemical vapor deposition (PCVD) process to form a seed layer followed by a conformal metal electroplating process are limited to low aspect ratio openings. As is known in the art, high aspect ratio vias are difficult to fill conformally, that is, without forming voids or keyholes that can adversely affect conductivity of the contacts.